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On This Day: British WWII Code Breaker Alan Turing Goes on Trial for Homosexuality

March 31, 2011 05:00 AM

by
findingDulcinea Staff

On March 31, 1952, Alan Turing, computer technology pioneer and breaker of the Nazi Enigma code, was put on trial for homosexual acts. Found guilty and ordered to undergo humiliating hormone therapy, Turing committed suicide two years later.

Alan Turing was a computer pioneer and key part of British code breaking efforts during World War II. But his homosexuality caused him personal and legal problems in post-war Britain, and eventually led to his suicide.

Found guilty of gross indecency, he was presented with a choice of prison or chemical therapy. He chose to receive injections of estrogen for a year, a procedure designed to curb his libido. This caused the humiliating enlargement of his breasts and an increase in body fat.

On June 7, 1954, before going to bed, Turing ate an apple injected with poison and was found dead the following morning. Though he left no note, his death is believed to be a suicide; biographer Andrew Hodges suggests that carried out the suicide so as to convince his mother that he accidentally ingested cyanide while conducting an experiment.

Alan Turing was born in London in 1912. As a young teenager, he developed a crush on a male classmate, who soon died of tuberculosis. “This loss shattered Turing's religious faith, writes Time, “and led him into atheism and the conviction that all phenomena must have materialistic explanations.”

Turing went on to study at King’s College in Cambridge, where he developed the Universal Turing Machine. The machine “embodies the essential principle of the computer: a single machine which can be turned to any well-defined task by being supplied with the appropriate program,” writes Hodges.

During World War II, Turing worked at Bletchley Park, the headquarters of Britain’s efforts to break German military codes, particularly the Enigma cipher. Building on Polish efforts, Turing devised a machine, called the Bombe, in spring 1940 that could eliminate billions of possibilities for the daily setting of the Enigma machine, allow code-breakers to decode messages within hours.

By the end of 1941, Turing developed a process, known as Banburismus, to crack the more complex Enigma code used by the German navy. As the war progressed, Bletchley Park code-breakers were able to decode thousands of messages a day, providing Britain’s defenses with vital intelligence.

After the war, Turing went to work for the National Physical Laboratory, where he attempted by build the Automatic Computing Engine, an electronic stored-program computer. His ambitious plans, however, were slowed by bureaucratic complications and shot down by NPL engineers, who built the simpler Pilot Model ACE.

In 1948, a frustrated Turing left the NPL for the Royal Society Computing Machine Laboratory at Manchester University, which had recently beat the NPL in building the first stored-program computer.

In 1950, Turing published a paper in the journal Mind that proposed a test, now known as the Turing test, for determining whether a machine has intelligence: if a human asking questions of a human and a machine cannot tell the difference between the two based on their answers, then the machine has intelligence. Turing theorized that one day it would be possible to build a machine with artificial intelligence.

In 2009, British Prime Minister Gordon Brown issued an apology to Turing. “He truly was one of those individuals we can point to whose unique contribution helped to turn the tide of war,” said Brown. “The debt of gratitude he is owed makes it all the more horrifying, therefore, that he was treated so inhumanely. … Alan and the many thousands of other gay men who were convicted as he was convicted, under homophobic laws, were treated terribly.”

Turing Archive for the History of Computing provides historical documents related to Alan Turing and the development of computing. The University of Canterbury in New Zealand and the University of San Francisco host the site.